rust/tests/ui/impl-trait/unsized_coercion.rs
2024-10-15 20:42:17 -04:00

23 lines
620 B
Rust

//! This test checks that opaque types get unsized instead of
//! constraining their hidden type to a trait object.
//@ revisions: next old
//@[next] compile-flags: -Znext-solver
//@[old] check-pass
trait Trait {}
impl Trait for u32 {}
fn hello() -> Box<impl Trait> {
//[next]~^ ERROR the size for values of type `dyn Trait` cannot be known at compilation time
if true {
let x = hello();
//[next]~^ ERROR: the size for values of type `dyn Trait` cannot be known at compilation time
let y: Box<dyn Trait> = x;
}
Box::new(1u32) //[next]~ ERROR: mismatched types
}
fn main() {}